External A/D USB converter

When I installed the latest update to HearThis, I saw the following message when it started up again, and I have some questions about it:

"To use HearThis to record audio Scriptures, you will need the following:

  1. A default recording and playback device capable of high-quality audio. Set up a headset microphone and (probably) an external A/D USB converter…"

There are some products available where I live that are in the USD 5 to 25 range. Is that the kind of thing that was being imagined when this was written? Can anyone show me an example of what this is supposed to mean?